Radial rotary piston machine

ABSTRACT

A radial rotary piston machine comprising a frame (1), at least one opening (13) for inlet of a medium into the machine and at least one opening (14) for discharge of a medium out of the machine, where the frame (1) comprises end plates (11) between which a rotor (2) is placed, this rotor (2) comprises axial opening (21) for a shaft (5) of the machine and further comprises at least two angularly offset piston chambers (22) transversely to the rotor axis, the shaft (5) of the machine extends through the axial opening (21) in the rotor (2) and is mounted in bearings in the end plates (11) of the frame (1), circular cams (51) are arranged on the shaft (5), the shaft (5) being positioned eccentrically to the rotor (2), each piston (4) is arranged for reciprocal movement in the chamber (22) and mounted rotatively on the circular cam (51), where the chamber (22) ends are closed by heads (3), the head (3) or the rotor (2) comprise at least one passage (32) for inlet and discharge of a medium from the chamber (22), which are opened and closed by valve means, where the head (3) and/or the rotor (2) comprise at least one passage (32) for inlet and discharge of a medium to and from the piston chamber (22) leading on one end in axial direction to the end plate (11) of the frame (1), and which is opened and closed at its axial opening by valve means in the form of separate arcuate slots (61).

TECHNICAL FIELD

The invention relates to a radial rotary piston machine, which can beused as a pump, compressor, vacuum pump or motor.

BACKGROUND ART

Rotary piston machines are known, particularly pumps or compressors,which comprise a rotor of circular section, in which chambers forpistons are formed, the pistons being mounted on circular cams toproduce their linear reciprocating motion, and these cams are mounted ona shaft, which is eccentrically positioned in relation to the rotor. Theeccentricity of axis of the shaft from axis of the rotor is equal to theeccentricity of the cam from the axis of the shaft.

Pumps or compressors of said type are disclosed, for example, indocuments U.S. Pat. Nos. 1,853,394, 1,910,876 and 4,723,895.

Document U.S. Pat. No. 1,853,394, discloses a rotary machine or pump,including a casing, a circular chamber within said casing having inletand, outlet ports at opposite sides thereof. A cylinder rotatablyconfined within said chamber having an axial opening, a pair of workingchambers extending at right angles to each other, diametrically throughsaid cylinder and at opposite sides of said opening thereof. Pistons,within said working chambers having circular openings therein, and arevoluble shaft having a pair of diametrically related integraleccentrics. Eccentrics operating within said piston openings. Said shaftbeing eccentrically mounted with respect to the axis of said circularchamber. The respective diameters of said eccentrics, piston openingsand axial cylinder opening being substantially equal and the diametersof said rotatable cylinder and said eccentrics being limited todimensions, in which the axial opening of said rotatable cylinder iscovered by each of said reciprocating pistons throughout its fullstroke. Object of the invention according to this document is to providean exceptionally efficient rotary machine for raising, transferring orcompressing liquids or gases.

Subsequent document U.S. Pat. No. 1,910,867, of the same applicant,which refers to the document U.S. Pat. No. 1,853,394, then discusses inmore detail properties of described rotary pump.

It is essential, with the pumps described in these documents, for theaxial opening in the cylinder to be continuously covered by the pistonsand never to be exposed, and thus no fluid could flow from one chamberof the cylinder to the other. This condition makes impossible to designa pump with the cylinder in one single piece, having a ratio of the pumprotor diameter and piston stroke of less than 5 to 1. This is because anassembling of the rotor with pistons can only be achieved by axiallymoving the drive shaft through the central opening of the rotor andcircular openings in the pistons. In order to make such assemblypossible, the central opening must have such cross section that thedrive shaft with the eccentrics can easily rotate therein. In addition,the lateral distance between the piston chambers must be approximatelythe same as the diameter of the piston, to allow the drive shaft torotate to the proper alignment of its eccentrics with respect to thecircular openings of the pistons, after one of the eccentrics has beenmoved through the circular opening of one of the pistons. Consequently,pumps with the ratio of less than 5 to 1 would be provided with anopening of such dimension that the reciprocating pistons would notcontinuously cover this opening and thus these pumps would be unusable.Design of the pump in FIGS. 5 to 10 of the document U.S. Pat. No.1,910,867 has the ratio of approximately 6 to 1. In order to assemblepumps of this type with the ratio of less than 5 to 1, the rotor must besplit to allow assembly with a smaller central opening.

However, the split rotor must show the same characteristics as a singlepiece rotor, and thus assembly of separate parts of the split rotor mustbe produced very precisely with minimal tolerances and also sufficientlyrigid. Such embodiment increases manufacturing demands and thus alsoproduction costs.

Document U.S. Pat. No. 4,723,895 discloses a method of and an apparatusfor effecting volume control suitable for use with a compressor forcompressing a compressible fluid, such as a refrigerant of therefrigeration cycle. A compressor is described in this document having aprinciple of operation of machines according to U.S. Pat. Nos.1,853,394, 1,910,876. Respective rotating parts of the compressor arejournalled by ball or roller bearings. The shaft of the compressor isformed integrally with circular cams. Each cam has such constructionthat the cam diameter is reduced without varying the eccentricity of thecam by causing a portion of the cam diametrically opposed to theprotuberance of the cam to be disposed in a position nearer to thecentre of the shaft than its outer circumferential surface, and reliefsfor assembling the pistons with the shaft are formed at the outercircumferential surface of the shaft in the vicinity of the portion ofthe cam diametrically opposed to the protuberance of the cam.

Said reliefs of the shaft are important for allowing the reduction indiameter of openings formed in the pistons, into which the cams areinserted to render possible the assembly of the shaft, the pistons andthe rotor in described arrangement. Disadvantage of the compressordesign according to the document U.S. Pat. No. 4,723,895 resides in tisconstruction complexity.

Document US 2015/0098841 A1 discloses a spin pump with spun-epicyclicgeometry, having pistons driven by eccentrics of circular section, asknown from the above-mentioned documents. This pump uses a split rotor,however, not in order to provide a longer piston travel, but in order toallow an assembly of the described pump without a need to divide thepiston into two pieces.

Intake and discharge with the above-described pump designs is providedby rotating a rotor in cylindric hole, where the body of the rotor opensand closes intake and discharge radial openings on cylindrical surfaceof the cylindric hole in the housing stator of the pump.

For the pump to operate correctly, it is necessary to produce veryprecise, tight, bearing of the rotor in the cylindric hole in thehousing stator of the pump, both due to providing a seal between theintake and discharge parts, and due to smooth rotation of the rotor anddrive shaft with circular cams. This requirement is extremely important,particularly in the case where these machines are intended for operationwithout a lubricant, that is as so-called oil-free. Providing thenecessary precision places higher demands on production requirements.

Not following the tight tolerances can result in leaks and unevenrunning of the machine, as is “jamming” in positions out of tolerances.

Such deficiency can be overcome to some extent by providing atransmission with ration 2:1 between the shaft and the rotor of thepump. Although such timing gear can facilitate the running and load ofworking parts of the pump, for example substantial lateral load onpistons, it however may be deleterious to the simplicity and efficiencyof the machine, as is for example mentioned in the US 2015/0098841 A1.

Document US 2015/0098841 A1 also discloses a pump embodiment where thepiston bore ends in rotor are coupled to heads. Valve plates may includevalves that regulate fluid inflow and fluid outflow routed to respectiveside ports in bearing plates. Thus, at least one valve is coupled to oneof the piston bores. In an embodiment, one of the valves is an outletvalve on a piston head and another valve is an inlet valve on a piston,whereby inflow may be drawn through the central crankcase portion of thepump and outflow discharged through the head. This embodiment exploitscheck valves known and used in heads of piston compressors. In theembodiment described, adverse effects derived from a rotation of thevalve plate around the axis of rotation of the rotor, i.e.centrifugal/centripetal forces, which would increase with the distanceof the valve plate from the axis of rotation of the rotor, can add todrawbacks of the known check valves originating particularly from theirown design. In this case, the rotor does not have to be of cylindricshape.

Object of the invention is rotary piston machine that can be used as apump, compressor, vacuum pump or motor, which is characterized bysimplicity in manufacturing, while practically eliminating alldisadvantages and limitations resulting from designs in theabove-described documents. Such rotary piston machine would allowproduction particularly of pumps, compressors and vacuum pumps for awide range of applications and pressure ranges while maintaining thesame construction arrangement.

It is also desirable for such construction, particularly of a compressoror vacuum pump, to be able to operate without a lubricant, or else inso-called oil-free operation.

DISCLOSURE OF INVENTION

Said object is achieved by a radial rotary piston machine according tothe invention comprising a frame, at least one opening for inlet of amedium into the machine and at least one opening for discharge of amedium out of the machine, where the frame comprises end plates betweenwhich a rotor is placed, this rotor comprises axial opening for a shaftof the machine and further comprises at least two angularly offsetpiston chambers transversely to the rotor axis, the shaft of the machineextends through the axial opening in the rotor and is mounted inbearings in the end plates of the frame, circular cams are arranged onthe shaft, the shaft being positioned eccentrically to the rotor, wherethe eccentricity of the axis of rotation of the shaft from the axis ofthe rotor is equal to the eccentricity of the axis of the circular camfrom the axis of rotation of the shaft, each piston is arranged forreciprocal movement in the piston chamber in the rotor and mountedrotatively on the circular cam on the shaft, where the piston chamberends are closed by heads, the head or the rotor comprise at least onepassage for inlet and discharge of a medium from the piston chamber,which are opened and closed by valve means. Rotary piston machineaccording to the invention is characterized in that the head and/or therotor comprise at least one passage for inlet and discharge of a mediumto and from the piston chamber leading on one end in axial direction tothe end plate of the frame, and which is opened and closed at its axialopening by valve means in the form of separate arcuate slots.

Preferably, the piston chamber is provided with an insert, and thisinsert is connected with the head of the piston chamber.

Preferably, the insert extends along the piston chamber to the proximityof the shaft of a pump, compressor or vacuum pump.

Preferably, the valve means in the form of separate arcuate slots areprovided in a valve plate positioned between the rotor end and the endplate of the frame.

Preferably, the rotor end is provided by a slide sealing plate with anaperture for passage of a medium to and from the passage in the headand/or rotor.

Preferably, the piston is provided at each of its ends by a piston ring,

Preferably, the piston ring is jointless, where the piston end isprovided removable for insertion of this jointless piston ring.

BRIEF DESCRIPTION OF DRAWINGS

The invention is for better understanding shown in accompanyingdrawings, in which:

FIG. 1 shows axonometric section view of radial rotary piston machine,specifically a compressor;

FIG. 2 shows axonometric expanded view of the machine of FIG. 1 ;

FIG. 3 shows axonometric expanded view of the valve means of themachine;

FIG. 4 shows axonometric view of the piston of the machine;

FIG. 5 shows axonometric view of the rotor of the machine without theslide sealing palate at one end of the rotor.

FIG. 6 shows axonometric expanded view of the rotor of the machine withthe slide sealing plates at both ends of the rotor and the valve plates;

FIG. 7 schematically shows working phase of the machine with the inletand discharge of a medium closed;

FIG. 8 schematically shows working phase of the machine with the intakeand discharge of a medium opened;

FIG. 9 shows overall outside view of the radial rotary piston machine ofFIG. 1 , in a frame in the form of closed casing with openings for inletand discharge of the air, and with protruding shaft of the machine.

FIG. 10 shows axonometric section view of a variant of the radial rotarypiston machine having pistons without piston rings, in the pistonchamber without the insert, without the slide sealing plates at the endsof the rotor, and with the passage for inlet and discharge of a mediumto or from the piston chamber, provided in the rotor;

FIG. 11 shows axonometric expanded view of the machine of FIG. 10 .

MODE(S) FOR CARRYING OUT THE INVENTION

Radial rotary piston machine according to the invention is explainedmore in detail in examples of embodiments shown in drawings.

A machine shown in FIGS. 1 to 6 is specifically a compressor, and arotary machine shown in FIGS. 10 and 11 can be a pump, or also a smallsize compressor.

The machine according to the examples shown is provided with two pistons4, each reciprocally movable in one chamber 22 of a rotor 2, wherechambers 22 are mutually arranged under 90° angle.

The machine, compressor according to FIGS. 1 to 6 , comprise a frame 1,in the shown example, in the form of two-piece casing. A rotor 2 isrotatively mounted in bearings 12 in end plates 11 of the frame 1, Axialopening 21 for a shaft 5 of the machine and chambers 22 for pistons 4are provided in the rotor 2.

The shaft 5 extends through axial opening 21 of the rotor 2 and isrotatably mounted in bearings 15 in the end plates 11 of the frame 1.The shaft 5 protrudes through the end plate 11 of the frame 1 on oneside, where it is sealed for example by a common shaft seal. Circularcams 51 are arranged on the shaft 5. The shaft 5 is positionedeccentrically to the rotor 2, where the eccentricity of the axis ofrotation of the shaft 5 from the axis of rotation of the rotor 2 isequal to the eccentricity of the axis of the circular cam 51 from theaxis of rotation of the shaft 5.

Circular cams 51 are mounted on the shaft 5 through detachable keyedjoint. This is preferable with regard to the production and also toassembling of the machine. However, it is equally possible to providethe shaft 5 with integral cams 51 as commonly known in the prior art.

A piston 4 is rotatively mounted on the circular cam 51. The piston 4has opening 41 to be mounted on the circular cam 51. This opening 41passes transversely through the centre of the piston 4, Thus, the piston4 has two ends, where the piston 4 is equipped with a piston ring 43 oneach of the two ends. The piston ring 43 is placed in a groove 42provided in the piston 4. The piston ring 43 with a joint or jointlesscan both be equally used. When jointless piston ring 43 is used,relative end of the piston 4 is made removable in order to make thegroove 42 accessible for insertion of such jointless piston ring 43.

In the example shown, the piston 4 is provided with one piston ring 43on each of its ends. One piston ring 43 on each end of the piston 4 issufficient, however, greater number of piston rings 43 can be chosen ifrequired, be it necessary regarding dimensions, or material of thepiston rings 43, or applications, which the machine according to theinvention will be used for.

The piston ring 43 provides tightness of the piston 4 in the pistonchamber 22 in the rotor 2, or tightness of the piston 4 in an insert 31of the piston chamber 22. It was surprisingly found that the piston ring43 also provides for smooth running of the machine without a need tofollow extremely tight tolerances in mutual positions of relatedrotating and moving parts, that is, the rotor 2, the shaft 5, circularcams 51, and pistons 4, as required in machines according to the priorart. Such required tight tolerances can be followed without anyconsiderable problems in machines having small dimensions, however, itis problematic to follow such tight tolerances in larger machines, whilethese require special and costly manufacturing. Not following therequired tolerances means for the prior art machines that due toinsufficient alignment of relative rotating and moving parts a jammingof these parts and uneven running can occur during the rotation. Thiscan be avoided either by increasing the power input on the shaft, oralso by including e.g. toothed transmission between the shaft 5 and therotor 2. Additional transmission thus virtually takes over driving therotor 2 instead of pistons 4.

When the piston 4 is placed in the chamber 22, or the insert 31, bymeans of the piston rings 34, related rotating moving parts, when themachine is running, are continually aligned in mutual ideal positionsensuring smooth operation of the machine. Then, manufacturing tolerancesin order of hundredths of a millimetre are sufficient, which by anymanner do not increase production costs due to a need of special precisemanufacturing. Thus, the machine runs completely smoothly, while thepiston 4 tightness is fully maintained, in fact, even from the machinestart-up.

The piston chamber 22 in the rotor 2 is closed by a head 3. The head 3is arranged on the rotor 2 detachably, and is provided on each end ofthe chamber 22. In the example shown, the head 3 is provided with theinsert. 33 of the piston chamber 22. In this case, the insert 31 createsthe inner space of the chamber 22, in which the piston 4 is moving, andtherefore, tight sliding placement of the piston 4 is formed by innerwall of the insert 31 and the piston ring 43. Preferably, the insert canbe provided such that it extends to the closest possible proximity ofthe shaft. 5, of course not disregarding a displacement of axes ofrotation of the shaft 5 and the rotor 2.

The insert 31 is preferable regarding its simple replacement whenworn-out, thus it is not necessary to replace, or optionally re-bore,the whole rotor 2, when directly chambers 22 are worn-out in case thepistons 4 move directly in the chambers 22 without the inserts 31.Further, the insert 31 allows that an interconnection of the chambers 22through the axial opening 21 in the rotor 2 cannot occur in case ofgreater dimensions of the machine and longer travels of the piston 4,when the piston 4 edge could pass under the outline of the axial opening21, thus creating undesired leak of a medium from the piston chamber 22to this axial opening 21. Then, this allows to produce the machinewithout for example a requirement for split rotor 2 in order to achievethe least possible diameter of axial opening 21 of the rotor 2.

At least one passage 32 is provided in the head 3 for inlet anddischarge of a medium to and from the piston chamber 22, in thisexample, the chamber 22 with the insert 31. When the piston chamber 22does not include the insert 31, this passage 32 can be provided also inthe head 3 only, or partially in the head 3 and partially in the body ofthe rotor 2, or in the body of the rotor 2 only, as will be describedlater in the example of embodiment according to FIGS. 10 and 11 .

The passage 32 provided in the body of the rotor 2 only can somehowdecrease volumetric efficiency of the compressor, however in the case ofpumps, or blowers this is negligible.

The passage 32 for inlet and discharge of a medium to and from thepiston chamber 22 is axially opening in direction to the end plate 11 ofthe frame 1, that is axially in regard to the rotor 2 and the shaft 5.

The description is the same also for the second piston 4 and the secondchamber 22 for the piston 22 of the machine according to this example ofembodiment.

Inlet and discharge of a medium to and from the piston chamber 22, inthis example the chamber 22 with the insert 31, is controlled by valvemeans for opening and closing of the inlet and discharge of a medium toand from the chamber 22. These valve means are provided in the form ofseparate arcuate slots 61 opening the passage 32 for inlet and dischargeof a medium to and from the chamber 22. Closing of the passage 32 iscarried by a solid part, the part between the separate arcuate slots 61,of the body in which the separate arcuate slots 61 are provided.

In the example shown, the arcuate slots 61 are preferably arranged in avalve plate 6, positioned between the rotor 2 and the bearing plate 11of the frame 1. The valve plate 6 is preferably lodged in a groove 16 inthe end plate 11 of the frame 1. However, the groove 16 is not essentialfor placing the valve plate 6. The valve plate 6 must be for properfunctioning secured against its own turning only. In the example shown,the position of the valve plate 6 is secured against turning by at leastone locking pin 63 interfering the plate 6 and the end plate 11. Inorder to secure position of the plate 6 it is of course possible to usealso other known suitable means.

Valve plate 6 of the type described is used in hydraulic axial pistonpumps, however its application in radial rotary piston machines is notdisclosed elsewhere, and in fact excluded in compressors known in theprior art.

In the example shown, preferably a sealing plate 7 is attached to theend of the rotor 2, in order to provide reliable sealing of the head 3and/or the rotor 2 against the valve plate 6, with regard to the passage32 for inlet and discharge of a medium. The sealing plate 7 comprises anaperture 71, in fact apertures 71, for passage of a medium to and fromthe passage 32 for inlet and discharge of a medium to and from thepiston chamber 22. Preferably in the case of the compressor, a sealing322 can be provided around axial opening of the passage 32 to preventaccidental leaks of pressure air between the sealing plate 7 and thehead 3 and/or the rotor 2. It is equally preferable when similar sealing64 is provided around the arcuate slot 61 on the valve plate 6 againstthe end plate 11.

Above description related to the valve means is the same also for theother end of the rotor 2.

The passage 32, i.e. passages 32, for inlet and discharge of a medium toor from the piston chamber 22, in the embodiment shown with the sealingplate 7 the apertures 71 for inlet and discharge of a medium are openedor closed respectively against the arcuate slots 61 of the valve plate6. Then, the arcuate slots 61 respectively communicate with an opening13 for inlet of a medium to the machine and an opening 14 for dischargea medium form the machine, which are arranged on the frame 1 of themachine.

In the example of embodiment of the machine shown in FIGS. 1 to 6 , theopening 13 for inlet of a medium to the machine is formed afterconnecting a two-pieces casing, which produces closed enclosure for thecompressor. The opening 13 connects inner space of the casing with asource of a medium, in this case the ambient air. The opening 14, i.e.openings 14, for discharge of a medium from the machine are provided inthe end plates 11 of the casing, while in this case they are led outform the groove 16 wherein the valve plate 6 is lodged.

Regarding the valve means, a variant of embodiment is possible forexample without the valve plate 6, where the arcuate slots 61 would beprovided directly in the end plates 11 of the frame 1. Equally, avariant of embodiment is possible without the slide sealing plate 7 atthe end of the rotor 2, where a slide surface would be directly endsurface of the rotor 2, whereon the passage 32 for inlet and dischargeof a medium to and from the piston chamber 22 would be provided. Suchvariant will be for a better understanding described in the next exampleof embodiment, which is shown in FIGS. 10 and 11 .

However, in general, the valve plate 6 and the slide sealing plate 7preferably provide sealing means that can be easily replaced whenworn-out.

In the example of embodiment of the machine shown, all rotative mountsare provided with roller bearings. Plain bearings can equally be used,or combinations of roller and plain bearings if required.

Radial rotary piston machine, the compressor, in described example ofembodiment shown in FIGS. 1 to 6 is working in the following way.

The shaft 5 connected to a drive (not shown) rotates the circular cams51, which drive the pistons 4 in reciprocating motion in their chambers22 with the inserts 31. The pistons 4 at the same time rotate the rotor2. Due to presence of the piston rings 43 the compressor runs completelysmoothly and evenly also with standard tolerances in positions andalignment of related rotative parts.

FIGS. 7 and 8 show positions of rotative parts when turning the shaft 5for 180°, where for a simpler illustration one extreme position of oneof the pistons 4 is chosen as starting position, i.e. the position atthe end of the piston 4 travel in the chamber 22. This starting positionis shown in FIG. 7 .

In the given starting position, the cam 51 is in extreme position of itshighest eccentricity, thus the piston 4 is in the extreme position atthe end of its travel. One end of the piston 4 is thus in the positionclosest to the head 3. The other end of the piston 4 is then in thefarthermost position from the head 3. Body of the valve plate 6 closesin this position the passages 32 for inlet and discharge of a medium toand from the piston chamber 22. In this case, when the sealing plate 7is present, the apertures 71 for passage of a medium are closed. In thephase described, the air is on one side in fact completely pushed outfrom the chamber 22 and on the other side, drawn in into the highestworking volume of the chamber 22.

Turning the shaft 5 further, the aperture on one side passes by the edgeof the arcuate slot 61 while connecting the chamber 22 with the airinlet. In the example shown, the air inlet is provided by the opening 13in the compressor casing, which supplies the air into the inner space ofthe casing. The air is guided from the inner space of the casino byinlet grooves 62 into the arcuate slot 61 in the valve plate 6.

At the same time, on the other side, the aperture 71 passes the edge ofthe other arcuate slot 61 while connecting the chamber 22 with the airdischarge. In the example shown, the air discharge is provided by theopening 14 in the end plate 11 of the casing, where this opening leadsto a channel 17 in the end plate 11 on the side of the valve plate 6.

The arcuate slots 61 in the valve plate 6 shown in drawings aresegmented, i.e. it is not continuous arcuate slot 61. The reason is tomaintain strength of the valve plate 6, while material of the plate 6between segments of the arcuate slot 61 does not affect the passage of amedium to and from the piston chamber 22 in any way. Anywhere theconstruction allows it, the slots 61 can be provided as continuous.Separation of the arcuate slots 61 regarding the separation of inlet anddischarge parts for a medium must of course be maintained.

In the case of a pump, i.e. pumping fluids, due to theirincompressibility, opening of the chamber 22 into the passages 32 mustoccur simultaneously. In the case of compressors, according torequirements for output pressure, edge of the discharge arcuate slot 61can be moved such that the passage 32, in this case the aperture 71, isclosed by the body of the valve plate 6 longer, resulting in compressionof the air while lowering the working volume of the chamber 22.

By turning the shaft 5 further, lowering of the chamber 22 volume abovethe piston 4 occurs on one end of the piston 4 and enlarging of thechamber 22 volume above the piston 4 occurs on the other end of thepiston 4, thus the air is pressed out on one side and drawn in on theother side.

In the position shown in FIG. 8 , the piston 4 is in the middleposition, passages 32, in this case also apertures 71, are fully opened.

By turning the shaft 5 further, volume of the chamber 22 on one end ofthe piston 4 is lowered, thus pressing the air out of the chamber 22continues, and volume of the chamber 22 on the other end of the piston 4is enlarging, thus drawing the air in into the chamber 22 continues.

The air is pressed out through the passage 32, in this example furtheralso through the aperture 71 in the sealing plate 7 into the arcuateslot 61 and form this into the opening 14 for discharge of a medium fromthe machine.

After the entire cycle is completed, i.e. with two revolutions of theshaft 5, the piston 4 is again in the position closest to the head 3 onone end, and in the farthermost position from the head 3 on the otherend. Body of the valve plate 6 in this position closes the passages 32,in this case the apertures 71 such that the air backflow between thechambers 22 above respective ends of the piston 4 cannot occur,

The way of operation described is the same also for variants of themachine, where for example the valve plate 6 and slide, sealing plate 7will not be used and the valve means will be provided directly in theframe 1 of the machine, in fact in the end plates 11.

In regard of a compressor, the most preferable is to create the frame 1in the form of the casing as shown in overall outside view in FIG. 9 .This way, compact machine is produced, where such casing protectsrotating parts of the machine and also contributes to lowering themachine noise. Furthermore, in case of the compressor, the rotor 2 isable to cool itself by own rotation in the surrounding drawn in medium,the air, such that no additional cooling equipment, such as a fan, isnecessary. Unlike known piston compressor, this compressor is capable ofuninterrupted operation, Cooling efficiency can further be increasedalso by injecting of a small amount of oil into the air drawn in.

In order to illustrate efficiency of the machine; the compressor,according to the example shown, particular dimensions and parameters ofthe compressor already produced are presented below.

Outer dimensions of the compressor casing, shown in FIG. 9 are140×140×180 mm. Compressor displacement is 90 cm³ per 1 revolution ofthe shaft 5. The compressor was driven by electric motor with 1.5 kWoutput. Noise, compressor output in l/min., and input were measured.Particular values measured at 800 rev./min. were:

-   -   noise 54 dBA, without acoustic covering    -   compressor output 60 l/min. at pressure 2 bar, input 280 W        compressor output 40 l/min. at pressure 8 bar, input 520 W

Overall, operation of the compressor was tested within revolutionsranging from 200 to 3500 rev./min. Maximum pressure measured so far was16 bar.

It can be derived from the arrangement of the machine according to theinvention that with dimensions of the outer casino being 200×200×270 mmthe compressor will have displacement of 305 cm³/rev., and withdimensions of the outer casing being 250×250×350 mm the compressor willhave displacement of 720 cm³/rev. The compressor having relatively smallouter dimensions will provide multiple times larger displacement volume.

When required, the frame 1 can also be for example provided such that itwill not form compact casing, but will form a frame structure providingnecessary mutual position and rigidity of the end plates 11. The opening13 for inlet of a medium to the machine will be then appropriatelyprovided on a body of the end plate 11.

FIGS. 10 and 11 show a variant of radial rotary piston machine accordingto the invention, that is complete rotor part of the machine with theshaft 5, with the pistons 4 without the rings 43, with piston chambers22 without the insert 31, without the slide sealing plates at the end ofthe rotor 2, and with the passage for inlet and discharge of a medium toand from the chamber 22 in the rotor 2 only. The machine with such rotorpart can be for example a pump, or a compressor having small dimensions,where tight tolerances can be followed due to the tightness andalignment of rotative parts of the machine. Pumps having largerdimensions looser tolerances are possible, as such tolerances arebalanced by the working fluid. Valve means, i.e. the arcuate slots 61,optionally valve plate 6, and also the slide sealing plate 7, and theiroptional combinations for this example of the machine are the same asdescribed in the example of embodiment according to FIGS. 1 to 6 . Theframe of the machine, as required, can be provided as the casing, oralso in the form of the frame structure, providing necessary mutualposition and rigidity of the end plates 11 as described above.

The way of operation of the machine according to the example ofembodiment shown in FIGS. 10 and 11 is the same as described above, ofcourse with the difference that parts present in the example ofembodiment shown in FIGS. 10 and 11 are considered.

Radial rotary piston machine according to the invention can be acompressor, pump, vacuum pump, or optionally also a motor.

Due to valve means described also reverse running of the machine ispossible without any additional arrangements, when in fact, only thefunction of the opening 13 for inlet of a medium to the machine isturned to the function of the opening 14 for discharge of a medium andvice versa.

Design of the radial rotary piston machine according to the inventionalso allows for producing a compressor as multi-stage compressor, forexample to obtain higher pressures. In the example of the compressordescribed and shown, the chambers 22 and the pistons 4 have the samedimensions, i.e. working volume of each chamber 22 is equally large.

In the case of multi-stage compressor, it is possible to provide onechamber 22 with larger volume, i.e. also with bigger piston 4 and onechamber with smaller volume, i.e. also with smaller piston 4. Then,intake of a medium would be realized into the chamber 22 with largervolume, and discharge from this larger chamber 22 would be supplied tothe intake of a media into the chamber 22 with smaller volume. Then,discharge of high-pressure media would be the discharge of a media fromthe chamber 22 with smaller volume.

Embodiments of the machine comprising more chambers 22 with pistons 4,or with different mutual angle as in the examples already described arenot excluded. However, in such cases, this will concern design solutionsof piston chambers 22 only and their arrangement in the rotor 2, whilethe essence of the solution will remain with all its advantages.

Radial rotary piston machine according to the invention can bemanufactured with technologies commonly available and used and withconventional materials.

Individual parts of the machine can also be produced using 3D printingwithout any problems. Use of special materials is anticipated only inspecial applications as for example oil-free compressors, pumps orcompressors for extreme loads and similar.

INDUSTRIAL APPLICABILITY

Radial rotary piston machine according to the invention can be used as acompressor, pump, vacuum pump, or also a motor.

Radial rotary piston machine as a compressor can be used for a widerange of applications in a wide range of pressures and flow rates, asfor example, blowers, low-pressure, middle-pressure or high-pressurecompressors.

Radial rotary piston machine as a vacuum pump can be used as efficientvacuum pump to create negative pressure, as well as multi-stage vacuumpump to reach high vacuum. The vacuum pump is simply provided only byconnecting the intake to a volume where a negative pressure is requiredwithout a demand for any further design adjustments.

1. A radial rotary piston machine comprising a frame, at least oneopening for inlet of a medium into the machine and at least one openingfor discharge of a medium out of the machine, where the frame comprisesend plates between which a rotor is placed, this rotor comprises axialopening for a shaft of the machine and further comprises at least twoangularly offset piston chambers transversely to the rotor axis, theshaft of the machine extends through the axial opening in the rotor andis mounted in bearings in the end plates of the frame, circular cams arearranged on the shaft, the shaft being positioned eccentrically to therotor, where the eccentricity of the axis of rotation of the shaft fromthe axis of the rotor is equal to the eccentricity of the axis of thecircular cam from the axis of rotation of the shaft, each piston isarranged for reciprocal movement in the piston chamber in the rotor andmounted rotatively on the circular cam on the shaft, where the pistonchamber ends are closed by heads, the head or the rotor comprise atleast one passage for inlet and discharge of a medium from the pistonchamber, which are opened and closed by valve means where the headand/or the rotor comprise at least one passage for inlet and dischargeof a medium to and from the piston chamber leading on one end in axialdirection to the end plate of the frame, and which is opened and closedat its axial opening by valve means in the form of separate arcuateslots.
 2. The radial rotary piston machine according to claim 1, whereinthe piston chamber is provided with an insert, and this insert isconnected with the head of the piston chamber.
 3. The radial rotarypiston machine according to claim 2, where the insert extends along thepiston chamber to the proximity of the shaft of the machine.
 4. Theradial rotary piston machine according to claim 1, where the separatearcuate slots are provided in a valve plate positioned between the rotorend and the end plate of the frame.
 5. The radial rotary piston machineaccording to claim 1, wherein the rotor end is provided by a slidesealing plate with an aperture for passage of a medium to and from thepassage in the head and/or rotor.
 6. The radial rotary piston machineaccording to claim 1, wherein the piston is provided at each of its endsby a piston ring.
 7. The radial rotary piston machine according to claim6, wherein the piston ring is jointless, where the piston end isprovided removable for insertion of this jointless piston ring.